Osteoarthritis (OA) affects an estimated 30% of Americans over 60 years of age and is one of the leading causes of reduced quality of life and loss of function for orthopaedic patients. Lower extremity OA is particularly common and costly. Estimates show that by 2030, over 4.4 million hip and knee replacement procedures will be performed annually in the United States with the number of hip replacements increasing by 200%. Innovative strategies are needed to more effectively diagnose, prevent and treat OA. Future treatment innovations will focus on early detection of disease and therapeutic interventions to prevent or halt disease progression and preserve the natural hip joint. Over the past decade there have been major advances in elucidating the pathophysiology of hip osteoarthritis. Most importantly, the profound etiological role of femoroacetabular impingement (FAI) has come to the forefront. FAI is characterized by structural deformities of the proximal femur and acetabulum that produce abnormal repetitive abutment along the acetabular rim resulting in excessive loading, acetabular rim cartilage damage and progressive joint degeneration. Patients with FAI present at various ages with diverse stages of disease. Due to the heterogeneous patient population and variability of disease characteristics, treatment of FAI encompasses a variety of musculoskeletal healthcare providers including orthopaedic surgeons (adult reconstruction, pediatrics, sports and trauma), rheumatologists, physiatrists, physical therapists and primary care physicians. Despite the recent interest and technical innovations for the surgical treatment of FAI, there is a major need for basic and clinical investigation in this burgeoning field. Additionally, significant controversy persists regarding the etiologic role of FAI in hip OA, the natural history of FAI, the pathophysiology of FAI, optimal diagnostic and disease staging modalities, the efficacy of different treatment techniques, and the most appropriate clinical outcome measures and optimal study designs for future clinical trials. Improved consensus regarding these issues will provide a foundation for future basic science investigations, clinical trials and improved clinical evidence to guide patient treatment. Advances in treating FAI are dependent upon improved understanding of the disease pathophysiology and determining the clinical efficacy and economic value of distinct treatment interventions. The 2012 AAOS Femoroacetabular Impingement research symposium will emphasize a multidisciplinary approach and will focus on summarizing current knowledge, developing consensus and identifying research strategies for several key issues related to FAI. Focus topics will include: 1) The etiology, epidemiology and societal impact of hip OA;2) The role of FAI in hip OA pathophysiology;3) The basic science of FAI;4) FAI disease screening, diagnostics, and disease staging;5) The relative effectiveness and outcomes of different treatment modalities and optimal clinical science methodologies;and 6) Strategies for future basic and clinical investigations. PUBLIC HEALTH RELEVANCE: Osteoarthritis (OA) affects an estimated 30% of Americans over 60 years of age and is one of the leading causes of reduced quality of life and loss of function for orthopaedic patients. Lower extremity OA is particularly common and costly. Estimates show that by 2030 over 4.4 million hip and knee replacement procedures will be performed annually in the United States with the number of hip replacements increasing by 200%. Femoroacetabular impingement (FAI) has recently come to the forefront as a potential precursor to hip osteoarthritis. There is a major need for improved consensus regarding the definition, diagnosis, treatment and etiological role of FAI relative to hip OA.